F. Lemos

Zeolite microporous solids : synthesis, structure, and reactivity

I. Synthesis.- Some thermodynamic and kinetic effects related to zeolite crystallization.- Organic and inorganic agents in the synthesis of molecular sieves.- Non-conventional crystalline microporous solids.- Molecular engineering of lamellar solids. I. Principles derived from the pillaring of smectite clays.- Molecular engineering of layered structures II. Synthetic approaches to some new pillared derivatives.- II. Characterization.- General overview of the characterization of zeolites.- Sorption of single gases and their binary mixtures in zeolites.- Frequency-response measurements of diffusion of sorbates in zeolites.- Diffraction Studies of zeolites.- Spectroscopic investigations of zeolite properties.- The impact of NMR spectroscopy in molecular sieve characterization I. Low Si/Al ratio materials.- The impact of NMR spectroscopy in molecular sieve characterization II. Investigations of highly siliceous systems.- III. Modification, Reactivity, and Catalytic Activity.- Modification of zeolites and new routes to ion-exchange.- Zeolite framework substitution reliable characterization methods.- Evaluation and tailoring of acid-base properties of zeolites Part 1.- Evaluation and tailoring of acid-base properties of zeolites Part 2.- Catalysis by exchanged cations and zeolite framework sites.- Zeolites in oil refining and petrochemistry.- Composition of the carbonaceous compounds responsible for zeolite deactivation. Modes of formation.- Deactivation of zeolites by coking. Prevention of deactivation and regeneration.- IV. Novel Developments and Vistas.- Molecular sieves with pore openings consisting of more than 12-T atoms.- Chemical bonding in zeolites.- Some aspects of molecular shape-selective catalysis with hydrocarbons in zeolites.- New applications of nonclassical molecular sieve catalysts.- Enzyme mimicking with zeolites.- Microporous materials in organic synthesis.- Concluding Remarks.- List of Participants.

The Acidity of Zeolites: Concepts, Measurements and Relation to Catalysis: A Review on Experimental and Theoretical Methods for the Study of Zeolite Acidity

In this article, we considered all aspects of acidity (nature of acid sites, strength, density, etc.) in solid catalysts and in zeolites in particular. After reminding the definition of acidity in liquid and solid acids, we emphasized acidity characterization by the most used physical techniques, such as Hammetts indicator titration, microcalorimetry of adsorbed probe molecules (ammonia, pyridine or other amines for acidity characterization and CO2 or SO2 for basicity characterization), ammonia or any amine thermodesorption, IR spectroscopy of hydroxyl groups and of several probe molecules adsorbed (ammonia, pyridine, piperidine, amines, CO, H2, etc.), MAS-NMR of 27Al, 29Si, 1H elements and of 1H, 13C, 31P, etc. of adsorbed probe molecules, and model catalytic reactions. Modeling the way the acid features of zeolites influence the catalytic activity of these catalysts toward acid-catalyzed reactions (relation between ammonia desorption activation energy values and catalytic activities, reaction mechanism, and kinetics) completes the general analysis of acidity and zeolite chemistry.

Activity–acidity relationship in zeolite ZSM-5. Application of Brönsted-type equations

In this paper the relation between activity and acidity in a variety of ZSM-5 zeolite catalysts, with different Si/Al ratios and different protonic content, is analysed and a quantitative correlation is obtained. The acid site strength distribution was estimated using temperature-programmed desorption (TPD) of ammonia by applying a digital deconvolution method to the curves. These data were then correlated with experimental catalytic activity data for the same catalysts towards n-heptane cracking reaction, by means of a Bronsted-type equation similar to the ones used for homogeneous acid catalysis and already used for other zeolites. It can be noticed that the same types of equation that are used for homogeneous acid catalysis also hold for heterogeneous acid catalysis and that the activation energy for ammonia desorption can be used as acid-strength scale for the purpose of correlation with catalytic activity.

Structure-activity relationship in zeolites

Abstract In this review we will try to give an integrated view of the relation between the structure and the catalytic behaviour of zeolitic materials, covering both the compositional and the structural aspects. Due to the amount of work that has been done in this wide area of zeolite catalysis this will, necessarily, be an incomplete although, hopefully, unbiased work. The paper will refer, not only to the relation that can be observed with natural and as-synthesised zeolites, but also to the wide range of techniques that are currently available for the ‘tuning’ of the catalytic properties of zeolitic materials. A special emphasis will be placed in all the aspects concerning shape selective catalysis, which is certainly the most striking form of a structure-activity relationship in heterogeneous catalysis.

Zeolites as supports for enzymatic hydrolysis reactions. Comparative study of several zeolites

Abstract Fusarium solani pisi recombinant cutinase was immobilised by adsorption on different zeolites and its activity towards the hydrolysis reaction of tricaprylin was measured. It was observed that the enzyme immobilised over most of the zeolites used (NaA, NaX, NaY, NaUSY and modified forms) was active for this reaction, although the specific activity depended strongly on the structure and composition of the zeolite support. This preliminary study of the use of zeolites as supports for enzymes was also extended by the analysis of the influence of the water content and of the thermal stability of one of the preparations. It can be concluded that the prospective use of zeolites as supports for enzymes in reactions involving organic media is very promising.

ZEOLITES AS SUPPORTS FOR AN ENZYMATIC ALCOHOLYSIS REACTION

A recombinant cutinase from Fusarium solani pisi was immobilized by adsorption on several zeolites and its activity towards the alcoholysis reaction of butyl acetate with hexanol, in organic media (isooctane), was measured as a function of the water content and water activity. The effects of the zeolite framework composition (including cation nature) and acidity were studied. The results were compared with other commonly used supports: polyamide Accurel-PA6, silica and alumina. Both the nature of the cation and the silica:alumina (Si:Al) ratio of the framework revealed to be important parameters. The most promising results were obtained for supports with little acidity and with lower Si:Al ratio. This last observation is in accordance with the results obtained with silica and alumina.

Influence of the cerium content of CeHY catalysts on their physicochemical and catalytic properties

Abstract The physicochemical and catalytic properties of a stabilized HY zeolite and of CeHY zeolites were compared. The Bro˝nsted acid sites of CeHY zeolites are definitely stronger than those of HY whereas their Lewis acid sites are weaker; the total number of acid sites decreases with the cerium content. The strength of protonic sites and the activity for n-heptane cracking at 350°C are maximal for an exchange rate of about 45%. For all the samples the cracking activity is clearly related to the strong protonic acidity. The rates and selectivities of the transformations of n-heptane and of its isomers (methylhexanes, 2,4-dimethylpentane) were compared. It can be shown that on all the catalysts, n-heptane cracking occurs through the classical carbenium ion chain mechanism in which the formation of nC 7 secondary carbenium ions is the limiting step; cracking products (essentially C 3 and iC 4 ) result mainly from the scission of 2,4- and 2,2-dimethyl carbenium ions,

Sustainable strategies for the upgrading of natural gas : fundamentals, challenges, and opportunities

Preface. Section I. Lectures. Natural Gas: Fuel or Feedstock? J.R. Rostrup-Nielsen. Molecular Chemistry of Alkane Activation F. Solymosi. Economics of Alkane Conversion J.-P. Lange. Theoretical Basis of the Activation of Light Alkanes M. Witko et al. Surface Organometallic Chemistry of Tantalum: Application to the Metathesis of Alkanes Catalyzed by a Tantalum Hydride Supported on Silica J. Thivolle-Cazat et al. The Challenges in Converting Remote Natural Gas to Valuable Products D. Trimm. Alternative Routes To Synfuel From Natural Gas D. Trimm. New Technologies for Light Alkane Upgrading. J. Gascon et al. Fundamentals of the Fischer-Tropsch Synthesis A.L. Lapidus. Reactor Technology for Syngas and Hydrogen E.H. Stitt. Engineering Alkanes to Olefins and Higher Value Chemicals D. Sanfilippo et al. Membrane Reactors For The Fischer-Tropsch Synthesis A.A. Khassin. Sources of methane for sustainable development V.N. Parmon. Section II. Communications. CO2 Separation by Membranes in Natural Gas Processing G. Clarizia, E. Drioli. Structural and Textural Properties of MCM-41 Mesoporous Molecular Sieves Containing Nb, V, Mo - Alternative Catalysts for Hydrocarbons Oxidation I. Nowak et al. Acidic and Catalytic Properties of Dealuminated BEA Zeolites J. P. Marques et al. Influence of the H-Ferrierite Sample on the Selectivity of Skeletal n-Butene Isomerization B. De Menorval et al. Study on the Lattice Defects in the Mixed Oxides of Neodymium and Alkaline Earth Elements and their Role on the Oxidative Coupling of Methane D. Filkova. Molecular Mechanism of the Methane Dissociation on the Vanadium Oxides Clusters. DFT Calculations W. Piskorz, E. Broclawik. Acidity, Activity and Micro-Kinetics Studies in a H-ZSM5 P. Borges et al. Microkinetic Model for Propane Activation over H-ZSM5 P. Borges et al. 13C MAS NMR Mechanistic Study of the Initial Stages of Propane Activation over Zn/H-MFI Catalyst Yu.G. Kolyagin et al. Dehydrogeflationof Propane over Chromium-Based Catalysts P. Michorczyk et al. Catalytic Oxidation of Methanol to Formaldehyde A. H. Yilmaz et al. Conversion of Gas Condensate over Metal-Containing MFI Catalysts A.G. Popov et al. Coke Formation on Alumina and Alumina Supported Platinum Catalysts Z. Sarbak. Activation Studies of the Cs-Doped Cu/ZnO Catalyst for the Higher Alcohol Synthesis L. Nowicki et al. Development of high temperature catalytic reactors for oxidative conversion of natural gas S. Cimino et al. The Effect of Process Conditions on Product Formation in Fischer-Tropsch Synthesis Sh.S. Itkulova. Mathematical Modeling of Steam Reforming Tubes with Shaped Particles A.P. Kagyrmanova et al. Application of NMR Microimaging for the Investigation of the Heterogeneous Catalytic Reactions Inside Catalyst Pellets and Fixed Catalyst Bed A.A. Lysova et al. Section III. Conclusions. Natural Gas as Feedstock J.C. Vedrine. Sustainable Strategies for the Upgrading of Natural Gas Eric G. Derouane. Participants. Subject Index. Author Index.

Influence of lanthanum content of LaHY catalysts on their physico-chemical and catalytic properties: Comparison with CeHY catalysts

Abstract The acidity and catalytic properties of LaHY zeolites, CeHY zeolites and HY zeolite are compared. The Bronsted acid sites of LaHY are stronger than those of CeHY and principally of HY. This was confirmed by a comparison of the reactivities of n-hexane, n-heptane, 2,4-dimethylbutane and 2,2,4-trimethylpentane. For the same exchange rate of rare earth cations, the activity of LaHY samples for n-heptane cracking is always higher than that of CeHY samples and the coke formation is slower. Both series present a maximum initial activity at the same ion-exchange rate (about 41% ); this value corresponds to the presence of one trivalent cation in the supercage of the zeolite. The exchange of HY by La3+ or by Ce3+ improved its thermal stability, probably owing to the formation of stable oxygen complexes between rare earth cations and lattice oxygen atoms. The improvement in thermal stability is more marked with La3+ than with Ce3+.

Principles and methods for accelerated catalyst design and testing

Table of Contents. Preface. Section 1: Lectures. Challenges and Strategies for the Implementation of Combinatorial Methods and High Throughput Testing in Heterogeneous Catalysis E.G. Derouane. Problems and Challenges About Accelerated Testing of the Catalytic Activity of Catalysts L. Petrov. Mass Transfer Limitations: A Bottleneck for High Throughput Screening in Multiphase Catalysis? C. de Bellefon. Combinatorial Methodology and its Experimental Validation by Parallel Synthesis, Testing And Characterization of Solid Catalytic Materials M. Baerns, et al. The Combinatorial Approach for Heterogeneous Catalysis: a Challenge for Academic Research D. Farrusseng, et al. An Evolutionary Strategy for the Design and Evaluation of High-Throughput Experiments D. Wolf. Organometallic Combinatorial Chemistry O. Lavastre, et al. Application of Genetic Algorithms to the Development and Optimisation of Light Paraffin Isomerisation Catalysts A. Corma, et al. Serial and Parallel Ways to Enhance and Accelerate Catalyst Testing P.P. Pescarmona, T. Maschmeyer. Rapid Catalyst Testing in The Boreskov Institute of Catalysis N.N. Bobrov, V.N. Parmon. Analysis and Modelling of Multi-Site Acid Catalysts F. Lemos, et al. Combinatorial and High Throughput Approaches in Heterogeneous Catalysis: Reality or Illusion C. Nacchace. Ultrafast Gas Chromatography V.N. Sidelnikov, et al. Section 2: Communications. Parallel Catalytic Synthesis of Phosphines and Related Ligands L. Xu, et al. Mixed Oxide Catalysts for Oxidation of Propane to Acrylic Acid: a Method for the Preparation of Realistic Catalyst Libraries and Their Quantitative Assessment L. Chen, et al. High Throughput Testing of Catalysts for the Hydrogenation of Carbon Monoxide to Ethanol O.M. Wilkin, et al. Transformation of Short Chain n-Alkanes on Dodecatungstophosphoric Acid and its Cesium Salts Ph. Bichon, et al. Complete Catalytic Oxidation of Methane and Ethane over Supported Platinum, Palladium and Manganese Oxide Catalysts G.C. Bond, et al. Rational Catalyst Selection and Optimization Versus Combinatorial? Case Study: Hydrogenolysys of Ethyl Laurate to 1-Dodecanol on Ru(Rh)-Sn(Re)/g-Al2O3 Catalysts S. Gobolos, et al. Studies on the Ultrasonic Enhancement of the Catalytic Activity in the Hydrogenation of Citral J.-P. Mikkola, et al. Future Trends in the Worldwide Oil Refining Industry R.P. Silvy. Catalyst Preparation and Testing for Catalytic Combustion of Chloromethanes S. Atalay, et al. Impulse Oscillation Model for Accelerated Catalyst Design M.A. Borowiak. Catalytic Oxidation of BINAP on (BINAp)Rh(co)cl K.A. Bunten, et al. Catalysts for Wastewater Treatment I. Castelo-Branco, et al. The Routes of Deep Oxidation Reactions on the CuCl2/Al2O3 Catalysts in the Ethylene Oxychlorination Process M.R. Flid, et al. The Catalytic Dehydrochlorination of Polychloroethanes in a Gas Phase M.A. Trushechkina, et al. The Bimetallic Co-Containing Supported on Alumina Catalysts in the Synthesis on the Base of Carbon Oxides Sh.S. Itkulova. Theoretical Investigations of Mo Catalysts in Olefin Metathesis J. Handzlik, J. Ogonowski. Differential Thermal Analysis and Thermal Gravimetry as Fast Methods to Test Catalytic Oxidation of Carbon Particulates Z. Sarbak, K. Surma. Aniline Methylation over Modified Micro- and Mesoporous Catalysts O.A. Ponomoreva, et al. Live Catalysis C. Lobato da Silva, et al. Section 3: Workshop. Accelerated Catalyst Preparation an